You probably already thought about it but you could do a whole series, or at least a couple of shows.
Discovering different chips on each show and posting the schematics/pin-layouts beforehand on the forum (like you did),
so listeners can build and experiment along wih the show.
Maybe you can even get some results back that you can play during the show.

Just as I was typing this out I noticed PHOBos has mentioned much of what I was... I too was thinking a section on your Inventions show where you talk about a particular IC would be really good. I was chatting to Psyingo earlier about Lunetta's and he was telling me all about the 4011 NAND gate. Perhaps a whole show about one IC might be stretching it too far, but a small section on a particular IC; its history, construction, overview of pins, applications etc would be really useful! And there are so many IC's out there! This could be a valuable resource...

And to anyone out there who hasn't done so already: go to the radio archives and give Les a listen! Well worth the visit!

By the way Les, your breadboards look immaculate! Very neat! Really curious about this Boolean Sequencer you have mentioned before...

-StevE-Last edited by -minus- on Thu Mar 04, 2010 7:01 am; edited 1 time in total

Thanks for the kind words guys. Yes I'm thinking of doing a series of shows on this topic. There will be at least one or two and hopefully more. I'll talk about the chips used and tell you how to get your own datasheets from the web. Yes the big thingy is a flat high-impedance piezo speaker (DigiKey part P11124-ND) that I bought years ago. The next show is a week from tommorrow so there's time to buy parts if you're so inclined...

I just got done drawing up a schematic and generating a parts list for the Boolean Sequencer Lunetta, which is project #2. I may cover it some in the first show, I dunno. It is actually two separate Boolean Sequencer Lunettas running from a common 555 clock. I like the second one better but they are both good.

Droffset, if you use 4093's then you can gate them with the AND gate outputs, leaving all four inputs of the AND gates for connection to the counter bits. It's just a different approach. I did it this way because I had no 4093's.

This show was the first beginner's Lunetta show. I started out with a jam on the Quad Osc Lunetta, talked about how to use a breadboard with lots of details like how to trim wires, a tour of the schematic, how a breadboard works, etc. and then finished up with a preview of next week's circuit. It was a pretty good show so give it a listen - especially if you like Lunettas!

The flat speaker: ("pricy but good quality") is from digikey.com, where Les buys most of his parts.

It's a piezo speaker with Frequency Range 150Hz ~ 100kHz. It's high impedance, meaning it can be driven directly from an opamp, or even directly from the CMOS

outputs.
After soldering two little pieces of 24G wire it's great for breadboarding says Les, and during the show it was miked and the sound directly sent to the stream.
I noticed no difference to my 4-osc-lunetta heard directly through headphones.

On the demo previously posted the 4-osc-lunetta was processed by e-ChucK, audio software Inventor actively promotes/supports at one of the EM forums.

-----------
Next the show discusses reading the 4-osc-lunetta schematic:

The four triangles with the little circle on the right side are the invertors.
Each invertor (oscillator) has a capacitor to ground at the input, and a potentiometer between it's output and input ( the "feedback loop").

There's a fixed resistor in the feedback path in series with the pot. Pitch rises with lower resistance. And higher resistance lowers pitch .
The 4.7K resistor thus limits the upper range, preventing the pitch to reach inaudible frequencies. (adjust to taste)

These extremely simple oscillators are used quite a lot in Lunetta's.

Next: the Voltage Followers.

An opamp with the signal to it's positive input and it's output connected to the negative input is voltage follower. Two of those are at the upper right of the

schematic.

The voltage followers are buffers used to reliably drive all kind of external amps , line in's etc, protecting your lunetta circuit and your external equipment from

oscillator (connected to the top voltage follower) to demo a square wave, the most common waveform generated by Lunetta's.

The R/2R ladder

This network of resistors combines electrical signals together with a binary weighting.
It is a DAC (digital to analog convertor).
The DAC is actually just a mixer. The top oscillator is called the MSB (most significent bit), having the highest level. Each next oscillator is attenuated to half of the

voltage of the more significant bit higher up the circuit. Thus the oscillator at the bottom of the schematic outputs the LSB (least significat bit), having the lowest

output.

Different combinations of the 4 bits (one from each oscillator) through this R/2R ladder (aka R/2R network) yields 16 different voltage values to be sent to the output.

Spares

In the lower left of the schematic are the unused portions of the IC's. Unused CMOS inputs are connected to ground, and unused opamp sections' positive inputs

First I build the Quad Osc. Lunetta (QLO) on a breadboard and then started the show. Since it started with the sounds of the QLO I could jam along with it .
I didn't have any 1M potentiometers though (only 5M but that didn't really work well) so I used LDR's. I never used opamps as voltage followers (at least not for audio) so thnx for the tip! ow, and I love the stereo output.

While listening I did some experiments and one of them was using a sequencer with LED outputs to control the LDR's. I got some really nice rhythms and sounds out of it. Next thing I did was making a second R2R ladder and connected the right channel (or the left,..ehm,. the one that was directly connected to the oscillator) to it. Then I connected the LSB to the MSB of the first R/2R ladder and the MSB to the LSB of the first R/2R. I used the 2 spare inverters to make 2 more oscillators to drive the remaing inputs of the second R/2R. great stereo sound!

Something I would like to know more about is protection of chips in lunettas. I mean, with all the patch cables it's easy to make a mistake and connect 2 or more outputs together, something CMOS chips usually don't really like. I think the easiest way is to use diodes on the outputs and pull up/down resisters on the inputs. Another way could be just connecting resistors in series with the ouputs (like 1K).

looking forward to the next show!

btw. The lunetta sounds where pretty loud so if possible turn the volume down a bit. The mic level was fine.

I didn't have any 1M potentiometers though (only 5M but that didn't really work well) so I used LDR's. /.../ Next thing I did was making a second R2R ladder and connected the right. channel (or the left,..ehm,. the one that was directly connected to the oscillator) to it. Then I connected the LSB to the MSB of the first R/2R ladder and the MSB to the LSB of the first R/2R. I used the 2 spare inverters to make 2 more oscillators to drive the remaing inputs of the second R/2R. great stereo sound!

Cool. I built the QOL on a piece of perfboard. Lack of 1M pots had me use 250K, with 0.47 uF caps. Works fine for audio range.
I've been poking at the circuit with other components, and one of my LEDs between pin 7 and 2 of the opamp was following the levels of the HR2R DAC very nicely. Makes a nice randomish LFO. LFO speed is not always predictable, but a multitude of waveforms are available.
Next time, for LFO function I'd like to use some bigger capacitors.

I was thinking to drive the spare invertor sections with this LED, but unfortunately I have misplaced my LDR's.
Also the spare opamp sections want LDR's for sequenced filtering. Mine do.
Anyway, with this simple two IC Lunetta a lot can be done.
The opamps are an addition I'll definitely be using more.
And I want more DACs as well. Very inspiring fun little schematic.

Oh, about the LED, maybe I should mention, I had 1k resistors in the feedbackpath of the opamp.
That's why I said my LED is between pin 7 and 2 specifically. With + side to pin 7.
Response varied with different LEDs, your milage may vary, as they say, but worth giving it a try.

Here was tonight's show about the Boolean Sequencer Lunetta went really good until i ran out of stuff to say! Then I just talked about different stuff and hooked up lunettas and made music, ending with a little jam session. It was fun to do and folks in the chat enjoyed it, so have a listen!

I can't believe I'm posting this show. It was pure chaos! I woke up an hour late and spent half an hour doing soundchecks, but you'll skip all that and this recording has me playing around with KS boards in what I'm told turned out to be a pretty good show after all. So enjoy!

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